The research reported on today found people who ran had a reduced risk of death from heart disease, as well as death from any cause, compared with non-runners.

Interestingly, a protective effect was seen regardless of running time, amount, duration, frequency or speed. People who ran just a modest amount – less than 51 minutes a week – also had a reduction in risk.

This equates to roughly seven minutes a day, although it should be noted this study did not specifically look at the effect of seven minutes of running a day.

These "modest" runners were found to have a 55% reduction in cardiovascular-associated death risk and a 30% reduction in any type of death compared with non-runners.

As many people cite lack of time as a barrier to regular exercise, this study should provide some encouragement – it suggests any exercise is better than none.

The study was carried out by researchers from Iowa State University, the University of South Carolina, and Louisiana State University System in the US, and the University of Queensland School of Medicine in Australia.

It was funded by the US National Institutes of Health and the Coca-Cola Company. The researchers state they have no relevant interests in or relationships with Coca-Cola.

The study was published in the peer-reviewed Journal of the American College of Cardiology.

The results of the study were reported appropriately by the UK media.

This was a cohort study that aimed to determine whether running reduces the risk of death during an average follow-up period of 15 years. The researchers were interested in death from any cause and death from cardiovascular disease.

Cohort studies cannot show running caused the reduction in risk of death, however. It is possible there were other differences between runners and non-runners that can explain the association seen.

There is also the possibility of reverse causality – that healthy people run more, rather than running making people healthy.

The researchers followed up 55,137 adults (average age 44 years) for an average of 15 years. Participants had not had a heart attack, stroke or cancer at the start of the study.

People were asked about how much running they did during the previous three months on a physical activity questionnaire, which included questions on duration, distance, frequency and speed.

Deaths were monitored during the follow-up period.

The researchers compared the risk of dying during follow-up for people who reported running during their leisure time with people who did not report running.

The researchers also looked at whether running time, distance, frequency (how often), amount (metabolic equivalent for a given speed multiplied by running time) or speed changed the association.

The researchers then analysed a subgroup of people who had completed the physical activity questionnaire twice to see if changes in running behaviour affected risk.

The researchers adjusted their analyses for:

Approximately 24% of people in the study ran. During follow-up, 3,413 people died and 1,217 deaths were from cardiovascular causes.

Compared with non-runners, runners had a 30% lower adjusted risk of death from any cause and a 45% lower adjusted risk of death from cardiovascular causes during follow-up. The researchers calculated from this that running increases life expectancy by three years.

The reduced risk of death during follow-up associated with running was similar even when people were subdivided according to how much and how intensely they ran.

Weekly running for less than 51 minutes, less than six miles, once or twice week, for less than 506 metabolic equivalent minutes (METs), or at less than six miles per hour was sufficient to reduce risk of mortality compared with not running. This 51 minutes of running per week corresponds to running just over seven minutes a day.

The researchers also found persistent runners had the most significant benefits, with 29% and 50% lower risk of all-cause and cardiovascular mortality, respectively, compared with people who have never been runners.

The researchers concluded this study has three main findings:

They go on to say that, "This study may motivate healthy but sedentary individuals to begin and continue running for substantial and attainable mortality benefits."

This well-conducted cohort study found running is associated with a reduction in risk of death from any cause and death from cardiovascular disease during a 15-year follow-up. It calculated running was associated with a three-year increase in life expectancy.

The study also found short duration running (less than 51 minutes a week, equivalent to less than approximately seven minutes a day) or running at slow speeds was associated with a reduction in risk.

As this was a cohort study, it cannot show running caused the reduction in risk of death. It is possible there were other differences between runners and non-runners that can explain the association seen. As the researchers note, a key factor that was not adjusted for in their analyses was diet.

There is also the possibility healthy people run more, rather than the act of running making people healthy. However, the researchers did perform a subgroup analysis where they analysed unhealthy individuals (who had an abnormal electrocardiogram, high blood pressure, diabetes, or hypercholesterolemia) and healthy individuals separately, and running was associated with a reduced risk of death in both groups.

Strengths of the study include its size and the long follow-up period. However, it was limited by the fact the majority of participants were white, middle to upper class adults. This means the results may not be applicable to other populations.

The study also relied on self-reporting to a certain extent. As people tend to overestimate the amount of exercise they do, this may mean there was in fact a greater protective effect of frequent modest running.

Even with these limitations in mind, the results of this study make for encouraging reading for those of us who find making time for regular exercise difficult. Even just 10 minutes of running or jogging before or after work could have significant long-term benefits for your health.

Exercise is known to be associated with a reduced risk of many chronic diseases, as well as boosting self-esteem, mood, sleep quality and energy, and reducing your risk of stress, depression, dementia and Alzheimer's disease.